Tesla's CEO Elon Musk pledged before his Twitter followers to sell 10% of his stock holdings to preempt new taxation laws, and Tesla's shares have slid nearly 10% since.
https://www.notebookcheck.net/Elon-Musk-s-Tesla-stock-Twitter-challenge-ends-in-a-US-100-billion-market-cap-loss.578112.0.html